Display apparatus having adjustable viewing angle range and method of driving the same

ABSTRACT

A display apparatus including a backlight module, first and second electrically-controlled elements, electrically-controlled first and second polarizers, a half-wave plate, and a display panel is provided. An included angle between first and second alignment directions of first and second alignment layers of the first electrically-controlled element is between 75 degrees and 105 degrees. An included angle between third and fourth alignment directions of third and fourth alignment layers of the second electrically-controlled element is between 165 degrees and 195 degrees. A first absorption axis of the first polarizer disposed between the backlight module and the first electrically-controlled element is perpendicular to a second absorption axis of the second polarizer disposed between the first and second electrically-controlled elements. The half-wave plate is disposed between the second polarizer and the second electrically-controlled element. The display panel is disposed on the second electrically-controlled element. A method of driving the display apparatus is provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of U.S. provisionalapplication Ser. No. 63/285,475, filed on Dec. 2, 2021. This applicationalso claims the priority of China application serial no. 202220271373.2,filed on Feb. 10, 2022. The entirety of the above-mentioned patentapplication is hereby incorporated by reference herein and made a partof this specification.

BACKGROUND Technical Field

The invention relates to a display apparatus and a method of driving thedisplay apparatus, and particularly relates to a display apparatushaving a viewing angle control function and a method of driving thedisplay apparatus.

Description of Related Art

In order to allow multiple viewers to watch a display image at the sametime, a display apparatus usually has a wide viewing angle displayeffect. However, in some situations or occasions, such as browsingprivate web pages, confidential information, or entering passwords inpublic, the wide viewing angle display effect is likely to cause theimage to be peeped by others, resulting in leakage of confidentialinformation. In order to achieve an anti-peep effect, a general practiceis to place a light control film (LCF) in front of a display panel tofilter out large-angle light, and set an electrically-controlleddiffuser on a light-emitting side of the light control film, such thatthe display apparatus may be switched between different display modes(such as a wide viewing angle mode and a narrow viewing angle mode).

In order to improve traffic safety, the above-mentioned displayapparatus may be designed to have a single-side anti-peep effect. Forexample: when a vehicle is running, a single-side anti-peep function isturned on, so that the display apparatus does not display images to adriver, but may display the images to a passenger. However, thearrangement of the light control film and the electrically-controlleddiffuser not only reduces an overall brightness of the displayapparatus, but also increases operating power consumption.

The information disclosed in this Background section is only forenhancement of understanding of the background of the describedtechnology and therefore it may contain information that does not formthe prior art that is already known to a person of ordinary skill in theart. Further, the information disclosed in the Background section doesnot mean that one or more problems to be resolved by one or moreembodiments of the invention was acknowledged by a person of ordinaryskill in the art.

SUMMARY

The invention is directed to a display apparatus with anelectrically-controlled viewing angle range and having smaller colorshift in a narrow viewing angle mode and a method of driving the displayapparatus.

Other objects and advantages of the invention may be further illustratedby the technical features broadly embodied and described as follows.

In order to achieve one or a portion of or all of the objects or otherobjects, an embodiment of the invention provides a display apparatus.The display apparatus includes a backlight module, a firstelectrically-controlled element, a second electrically-controlledelement, a first polarizer, a second polarizer, a half-wave plate, and adisplay panel. The first electrically-controlled element is disposed onthe backlight module and includes a first liquid-crystal layer, a firstalignment layer, and a second alignment layer. The first liquid-crystallayer is sandwiched between the first alignment layer and the secondalignment layer. An included angle between a first alignment directionof the first alignment layer and a second alignment direction of thesecond alignment layer is between 75 degrees and 105 degrees. The secondelectrically-controlled element is disposed on the firstelectrically-controlled element and includes a second liquid-crystallayer, a third alignment layer, and a fourth alignment layer. The secondliquid-crystal layer is sandwiched between the third alignment layer andthe fourth alignment layer. An included angle between a third alignmentdirection of the third alignment layer and a fourth alignment directionof the fourth alignment layer is between 165 degrees and 195 degrees. Anincluded angle between the second alignment direction and the thirdalignment direction is between 30 degrees and 60 degrees, or between 120degrees and 150 degrees. The first polarizer is provided between thebacklight module and the first electrically-controlled element, and hasa first absorption axis parallel or perpendicular to the first alignmentdirection. The second polarizer is provided between the firstelectrically-controlled element and the second electrically-controlledelement, and has a second absorption axis. An axial direction of thesecond absorption axis is perpendicular to an axial direction of thefirst absorption axis. The half-wave plate is provided between thesecond polarizer and the second electrically-controlled element. Thedisplay panel is disposed on the second electrically-controlled element.

In order to achieve one or a portion of or all of the objects or otherobjects, an embodiment of the invention provides a method of driving adisplay apparatus. The method of driving the display apparatus includesproviding the display apparatus, providing a first voltage to a firstelectrically-controlled element and a second electrically-controlledelement of the display apparatus to operate the display apparatus in awide viewing angle mode, and providing a second voltage and a thirdvoltage to the first electrically-controlled element and the secondelectrically-controlled element, respectively, to operate the displayapparatus in a narrow viewing angle mode. The first voltage is smallerthan the second voltage and the third voltage. The display apparatusfurther includes a backlight module, a first polarizer, a secondpolarizer, a half-wave plate, and a display panel. The firstelectrically-controlled element is disposed on the backlight module andincludes a first liquid-crystal layer, a first alignment layer, and asecond alignment layer. The first liquid-crystal layer is sandwichedbetween the first alignment layer and the second alignment layer. Anincluded angle between a first alignment direction of the firstalignment layer and a second alignment direction of the second alignmentlayer is between 75 degrees and 105 degrees. The secondelectrically-controlled element is disposed on the firstelectrically-controlled element and includes a second liquid-crystallayer, a third alignment layer, and a fourth alignment layer. The secondliquid-crystal layer is sandwiched between the third alignment layer andthe fourth alignment layer. An included angle between a third alignmentdirection of the third alignment layer and a fourth alignment directionof the fourth alignment layer is between 165 degrees and 195 degrees. Anincluded angle between the second alignment direction and the thirdalignment direction is between 30 degrees and 60 degrees, or between 120degrees and 150 degrees. The first polarizer is provided between thebacklight module and the first electrically-controlled element, and hasa first absorption axis parallel or perpendicular to the first alignmentdirection. The second polarizer is provided between the firstelectrically-controlled element and the second electrically-controlledelement, and has a second absorption axis. An axial direction of thesecond absorption axis is perpendicular to an axial direction of thefirst absorption axis. The half-wave plate is provided between thesecond polarizer and the second electrically-controlled element. Thedisplay panel is disposed on the second electrically-controlled element.

Based on the above, in the display apparatus of an embodiment of theinvention, the electrically-controlled first liquid-crystal layer andsecond liquid-crystal layer are provided between the backlight moduleand the display panel. The included angle between the alignmentdirection on one side of the first liquid-crystal layer and thealignment direction on the other side thereof is between 75 degrees and105 degrees, and the included angle between the alignment direction onone side of the second liquid-crystal layer and the alignment directionon the other side thereof is between 165 degrees and 195 degrees,wherein the included angle between the alignment direction of the firstliquid-crystal layer close to the second liquid-crystal layer and thealignment direction of the second liquid-crystal layer close to thefirst liquid-crystal layer is between 30 degrees and 60 degrees, orbetween 120 degrees and 150 degrees, and two opposite sides of the firstliquid-crystal layer are provided with two polarizers with absorptionaxes perpendicular to each other. Through the above configuration, theviewing angle range of the display apparatus in at least one directionmay be electrically-controlled and switched to meet different usagesituations.

Other objectives, features and advantages of the present invention willbe further understood from the further technological features disclosedby the embodiments of the present invention wherein there are shown anddescribed preferred embodiments of this invention, simply by way ofillustration of modes best suited to carry out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a schematic cross-sectional view of a display apparatusaccording to the first embodiment of the invention.

FIG. 2A and FIG. 2B are schematic diagrams showing the arrangementrelationship between the alignment direction of the alignment layer, theaxial directions of the absorption axes of the polarizers, and the axialdirection of the slow axis of the half-wave plate of FIG. 1 .

FIG. 3A and FIG. 3B are transmittance distribution diagrams of thedisplay apparatus of FIG. 1 operated in different display modes.

FIG. 4 is a luminance-viewing angle curve diagram of the displayapparatus of FIG. 1 operated in different display modes.

FIG. 5A to FIG. 5D are transmittance distribution diagrams of a displayapparatus when the first electrically-controlled element of FIG. 1 isoperated at different voltages.

FIG. 6 is a luminance-viewing angle curve diagram of a display apparatuswhen the first electrically-controlled element of FIG. 1 is operated atdifferent voltages.

FIG. 7A to FIG. 7C are transmittance distribution diagrams of a displayapparatus when the second electrically-controlled element of FIG. 1 isoperated at different voltages.

FIG. 7D is a luminance-viewing angle curve diagram of a displayapparatus when the second electrically-controlled element of FIG. 1 isoperated at different voltages.

FIG. 8A is a schematic cross-sectional view of the backlight module ofFIG. 1 .

FIG. 8B is a schematic cross-sectional view of another implementation ofthe backlight module of FIG. 1 .

FIG. 9 is a schematic cross-sectional view of a display apparatusaccording to the second embodiment of the invention.

FIG. 10A is a schematic diagram illustrating the arrangementrelationship between the alignment direction of the alignment layer, theaxial directions of the absorption axes of the polarizers, and the axialdirection of the slow axis of the half-wave plate of FIG. 9 .

FIG. 10B is a schematic diagram illustrating another arrangementrelationship between the alignment direction of the alignment layer, theaxial directions of the absorption axes of the polarizers, and the axialdirection of the slow axis of the half-wave plate of FIG. 9 .

FIG. 11A and FIG. 11B are transmittance distribution diagrams of thedisplay apparatus of FIG. 9 operated in different display modes.

FIG. 12 is a schematic cross-sectional view of a display apparatusaccording to the third embodiment of the invention.

FIG. 13 is a schematic diagram illustrating the arrangement relationshipbetween the alignment direction of the alignment layer, the axialdirections of the absorption axes of the polarizers, and the axialdirection of the slow axis of the half-wave plate of FIG. 12 .

FIG. 14A and FIG. 14B are transmittance distribution diagrams of thedisplay apparatus of FIG. 12 operated in different display modes.

FIG. 15 is a luminance-viewing angle curve diagram of the displayapparatus of FIG. 12 and the display apparatus of FIG. 1 operated in anarrow viewing angle mode.

DESCRIPTION OF THE EMBODIMENTS

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings which form a part hereof,and in which are shown by way of illustration specific embodiments inwhich the invention may be practiced. In this regard, directionalterminology, such as “top,” “bottom,” “front,” “back,” etc., is usedwith reference to the orientation of the Figure(s) being described. Thecomponents of the present invention can be positioned in a number ofdifferent orientations. As such, the directional terminology is used forpurposes of illustration and is in no way limiting. On the other hand,the drawings are only schematic and the sizes of components may beexaggerated for clarity. It is to be understood that other embodimentsmay be utilized and structural changes may be made without departingfrom the scope of the present invention. Also, it is to be understoodthat the phraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless limited otherwise, the terms“connected,” “coupled,” and “mounted” and variations thereof herein areused broadly and encompass direct and indirect connections, couplings,and mountings. Similarly, the terms “facing,” “faces” and variationsthereof herein are used broadly and encompass direct and indirectfacing, and “adjacent to” and variations thereof herein are used broadlyand encompass directly and indirectly “adjacent to”. Therefore, thedescription of “A” component facing “B” component herein may contain thesituations that “A” component directly faces “B” component or one ormore additional components are between “A” component and “B” component.Also, the description of “A” component “adjacent to” “B” componentherein may contain the situations that “A” component is directly“adjacent to” “B” component or one or more additional components arebetween “A” component and “B” component. Accordingly, the drawings anddescriptions will be regarded as illustrative in nature and not asrestrictive.

FIG. 1 is a schematic cross-sectional view of a display apparatusaccording to the first embodiment of the invention. FIG. 2A and FIG. 2Bare schematic diagrams showing the arrangement relationship between thealignment direction of the alignment layer, the axial directions of theabsorption axes of the polarizers, and the axial direction of the slowaxis of the half-wave plate of FIG. 1 . FIG. 3A and FIG. 3B aretransmittance distribution diagrams of the display apparatus of FIG. 1operated in different display modes. FIG. 4 is a luminance-viewing anglecurve diagram of the display apparatus of FIG. 1 operated in differentdisplay modes. FIG. 5A to FIG. 5D are transmittance distributiondiagrams of a display apparatus when the first electrically-controlledelement of FIG. 1 is operated at different voltages. FIG. 6 is aluminance-viewing angle curve diagram of a display apparatus when thefirst electrically-controlled element of FIG. 1 is operated at differentvoltages. FIG. 7A to FIG. 7C are transmittance distribution diagrams ofa display apparatus when the second electrically-controlled element ofFIG. 1 is operated at different voltages. FIG. 7D is a luminance-viewingangle curve diagram of a display apparatus when the secondelectrically-controlled element of FIG. 1 is operated at differentvoltages. FIG. 8A is a schematic cross-sectional view of the backlightmodule of FIG. 1 . FIG. 8B is a schematic cross-sectional view ofanother implementation of the backlight module of FIG. 1 .

Referring to FIG. 1 , a display apparatus 10 includes a backlight module100, a first electrically-controlled element 210, a secondelectrically-controlled element 220, a first polarizer POL1, a secondpolarizer POL2, a half-wave plate 250, and a display panel 300. Thefirst electrically-controlled element 210 is disposed on the backlightmodule 100. The second electrically-controlled element 220 is disposedon the first electrically-controlled element 210, for example, the firstelectrically-controlled element 210 is disposed between the secondelectrically-controlled element 220 and the backlight module 100. Thedisplay panel 300 is disposed on the second electrically-controlledelement 220, for example, the second electrically-controlled element 220is disposed between the first electrically-controlled element 210 andthe display panel 300. The first polarizer POL1 is disposed between thebacklight module 100 and the first electrically-controlled element 210.The second polarizer POL2 is disposed between the firstelectrically-controlled element 210 and the secondelectrically-controlled element 220. The half-wave plate 250 is disposedbetween the second polarizer POL2 and the second electrically-controlledelement 220. Namely, in the embodiment, the first polarizer POL1, thefirst electrically-controlled element 210, the second polarizer POL2,the half-wave plate 250, the second electrically-controlled element 220,and the display panel 300 are sequentially disposed on the backlightmodule 100 in a direction Z (as shown in FIG. 1 ). The display panel 300is, for example, a liquid-crystal display panel, or other suitablenon-self-luminous display panels.

In detail, the first electrically-controlled element 210 includes afirst substrate SUB1, a second substrate SUB2, a first electrode layerE1, a second electrode layer E2, a first alignment layer AL1, a secondalignment layer AL2, and a first liquid-crystal layer LCL1. The firstelectrode layer E1 and the first alignment layer AL1 are provided on aside surface of the first substrate SUB1 facing the second substrateSUB2. The second electrode layer E2 and the second alignment layer AL2are provided on a side surface of the second substrate SUB2 facing thefirst substrate SUB1. The first liquid-crystal layer LCL1 is sandwichedbetween the first alignment layer AL1 and the second alignment layerAL2.

Similarly, the second electrically-controlled element 220 includes athird substrate SUB3, a fourth substrate SUB4, a third electrode layerE3, a fourth electrode layer E4, a third alignment layer AL3, a fourthalignment layer AL4 and a second liquid-crystal layer LCL2. The thirdelectrode layer E3 and the third alignment layer AL3 are provided on aside surface of the third substrate SUB3 facing the fourth substrateSUB4. The fourth electrode layer E4 and the fourth alignment layer AL4are provided on a side surface of the fourth substrate SUB4 facing thethird substrate SUB3. The second liquid-crystal layer LCL2 is sandwichedbetween the third alignment layer AL3 and the fourth alignment layerAL4.

Referring to FIG. 2A and FIG. 2B, an included angle γ1 between a firstalignment direction AD1 of the first alignment layer AL1 and a secondalignment direction AD2 of the second alignment layer AL2 is between 75degrees and 105 degrees. An included angle γ2 between a third alignmentdirection AD3 of the third alignment layer AL3 and a fourth alignmentdirection AD4 of the fourth alignment layer AL4 is between 165 degreesand 195 degrees. An included angle γ3 between the second alignmentdirection AD2 and the third alignment direction AD3 is between 30degrees and 60 degrees, or between 120 degrees and 150 degrees. In theembodiment, the included angle γ1 between the first alignment directionAD1 and the second alignment direction AD2 is, for example, 90 degrees,the included angle γ2 between the third alignment direction AD3 and thefourth alignment direction AD4 is, for example, 175 degrees, and theincluded angle γ3 between the second alignment direction AD2 and thethird alignment direction AD3 is, for example, 40 degrees.

Namely, a plurality of liquid-crystal molecules LC1 in the firstliquid-crystal layer LCL1 are arranged in a twist manner along thedirection Z (as shown in FIG. 1 ), i.e., the firstelectrically-controlled element 210 may be a twisted nematic (TN)-typeelectrically-controlled liquid-crystal cell. A plurality ofliquid-crystal molecules LC2 in the second liquid-crystal layer LCL2 aregenerally arranged in parallel with each other (as shown in FIG. 1 ),i.e., the second electrically-controlled element 220 may be anelectrically-controlled birefringence (ECB)-type liquid-crystal cell.Since the first electrically-controlled element 210 and the secondelectrically-controlled element 220 of the embodiment adopt differentliquid-crystal driving modes, the color shift of light coming from thebacklight module 100 after passing through these electrically-controlledelements may be effectively suppressed.

In the embodiment, the display apparatus 10 has a first viewing anglecontrol direction parallel to a direction X (for example, perpendicularto the direction Z). More specifically, a viewing angle range of thedisplay apparatus 10 along the first viewing angle control direction iselectrically adjustable. In the embodiment, the first alignmentdirection AD1 of the first alignment layer AL1 is perpendicular to thesecond alignment direction AD2 of the second alignment layer AL2,wherein an included angle α1 between the first alignment direction AD1and the direction X is, for example, 135 degrees, and an included angleα2 between the second alignment direction AD2 and the direction X is,for example, 45 degrees, but the invention is not limited thereto. Inanother embodiment, the included angle α1 may also be 45 degrees, andthe included angle α2 may also be 135 degrees.

Preferably, in the embodiment, an axial direction of a first absorptionaxis AX1 of the first polarizer POL1 may be optionally parallel to thefirst alignment direction AD1 of the first alignment layer AL1, and anaxial direction of the second absorption axis AX2 of the secondpolarizer POL2 may be optionally parallel to the second alignmentdirection AD2 of the second alignment layer AL2. Namely, the axialdirection of the first absorption axis AX1 is perpendicular to the axialdirection of the second absorption axis AX2, an included angle β1between the first absorption axis AX1 and the direction X is 135degrees, and an included angle β2 between the second absorption axis AX2and the direction X is 45 degree. However, the invention is not limitedthereto. In other embodiments, the axial direction of the firstabsorption axis AX1 of the first polarizer POL1 may be perpendicular tothe first alignment direction AD1 of the first alignment layer AL1, andthe axial direction of the second absorption axis AX2 of the secondpolarizer POL2 may be perpendicular to the second alignment directionAD2 of the second alignment layer AL2.

In the embodiment, an included angle α3 between the third alignmentdirection AD3 of the third alignment layer AL3 and the direction X(i.e., the first viewing angle control direction) is, for example, 85degrees, and an included angle α4 between the fourth alignment directionAD4 of the fourth alignment layer AL4 and the direction X is, forexample, −90 degrees. It should be noted that the negative value of theangle here means that the angle is defined based on the direction X andaccording to an angle magnitude that deviates from the direction X in aclockwise direction; on the contrary, if the angle is positive, it isdefined based on the direction X and according to an angle magnitudethat deviates from the direction X in a counterclockwise direction.

Moreover, an included angle θ between a slow axis SX of the half-waveplate 250 and the direction X is between 50 degrees and 80 degrees orbetween 140 degrees and 170 degrees. In the embodiment, the includedangle θ is, for example, 65 degrees. Namely, an axial direction of theslow axis SX of the half-wave plate 250 of the embodiment is between thesecond absorption axis AX2 of the second polarizer POL2 and the thirdalignment direction AD3 of the third alignment layer AL3.

Specifically, when the display apparatus 10 is operated in a wideviewing angle mode, a first voltage is provided to the firstelectrically-controlled element 210 and the secondelectrically-controlled element 220. When the display apparatus 10 isoperated in a narrow viewing angle mode, a second voltage is provided tothe first electrically-controlled element 210 and a third voltage isprovided to the second electrically-controlled element 220. Inparticular, the first voltage is lower than the second voltage, and thefirst voltage is lower than the third voltage. Specifically, the viewingangle range of the wide viewing angle mode is larger than the viewingangle range of the narrow viewing angle mode, and the viewing anglerange is, for example, a viewing angle range corresponding to abrightness greater than a certain threshold brightness.

In other words, a method of driving the display apparatus 10 includesproviding the first voltage to the first electrically-controlled element210 and the second electrically-controlled element 220 to operate thedisplay apparatus 10 in the wide viewing angle mode, and respectivelyproviding the second voltage and the third voltage to the firstelectrically-controlled element 210 and the second electricallycontrolled element 220 to operate the display apparatus 10 in the narrowviewing angle mode.

For example, in the embodiment, when the voltage between the firstelectrode layer E1 and the second electrode layer E2 of the firstelectrically-controlled element 210 and the voltage between the thirdelectrode layer E3 and the fourth electrode layer E4 of the secondelectrically-controlled element 220 are both 0 V (i.e., the firstvoltage), as shown in FIG. 3A, the viewing angle ranges of the displayapparatus 10 at different azimuth angles are substantially the same.

When the voltage between the first electrode layer E1 and the secondelectrode layer E2 of the first electrically-controlled element 210 is1.7 V (i.e., the second voltage), and the voltage between the thirdelectrode layer E3 and the fourth electrode layer E4 of the secondelectrically-controlled element 220 is 3.5 V (i.e., the third voltage),as shown in FIG. 3B, the display apparatus 10 has a narrow viewing anglerange in the direction parallel to the direction X, for example, thelight emitted to side viewing angle ranges (the left side and the rightside of the front view angle direction) may be effectively suppressed.Therefore, the direction parallel to the direction X of FIG. 3B may bedefined as the first viewing angle control direction of the displayapparatus 10. It should be noted that the transmittance distribution(viewing angle) of the display apparatus 10 at this time is asymmetricwith respect to the front viewing direction (e.g., the direction Z).

Further, referring to FIG. 4 at the same time, a curve C1 and a curve C2are respectively curves of brightness (or luminance) to viewing angle inthe horizontal direction (e.g., parallel to the direction X) when thedisplay apparatus 10 is operated in the wide viewing angle mode and thenarrow viewing angle mode. When the display apparatus 10 is operated inthe narrow viewing angle mode, a narrow viewing angle brightnessdistribution curve (i.e., the curve C2) thereof clearly shows that thelight output in the side viewing angle range above −30 degrees iseffectively suppressed, and the viewing angle corresponding to themaximum brightness of the narrow viewing angle brightness distributioncurve is deviated from the front viewing angle (i.e., 0 degree) andbiased towards a larger viewing angle (as shown in FIG. 4 , the viewingangle corresponding to the maximum brightness is, for example, 3degrees).

It should be noted that the above narrow viewing angle brightnessdistribution curve has a main viewing angle range covering the frontviewing angle. The main viewing angle range has a peak (for example, themaximum brightness), and the peak is moved along the direction X as theapplied voltage of the first electrically-controlled element 210 ischanged. In other words, the method of driving the display apparatus 10may further includes tuning the applied voltage (i.e., the secondvoltage) of the first electrically-controlled element 210 when thedisplay apparatus 10 is operated in the narrow viewing angle mode.

For example, referring to FIG. 1 and FIG. 5A to FIG. 5D, FIG. 5A to FIG.5D are respectively transmittance distribution diagrams of the displayapparatus 10 when the applied voltage of the firstelectrically-controlled element 210 is 1.6 V, 1.7 V, 1.8 V, and 1.9 V,and the applied voltage of the second electrically-controlled element220 is 3.5 V. According to the figures, it is known that the higher theapplied voltage of the first electrically-controlled element 210 is, themore the viewing angle range located on the left side of the front viewangle direction is reduced toward the direction X. Referring to FIG. 6 ,a curve C3, a curve C2, a curve C4, and a curve C5 respectively showbrightness-viewing angle distributions of the display apparatus 10 alongthe direction X (or the first viewing angle control direction) of FIG.5A to FIG. 5D including the front viewing angle when the firstelectrically-controlled element 210 is applied with voltages of 1.6 V,1.7 V, 1.8 V, and 1.9 V. The viewing angle corresponding to the peak ofthe narrow viewing angle brightness distribution curve is moved alongthe direction X as the applied voltage (i.e., the second voltage) of thefirst electrically-controlled element 210 is increased, i.e., theviewing angle corresponding to the peak may be increased.

It should be noted that when the display apparatus 10 is used invehicle, due to design requirements of different vehicle models, therelative position relationship between the display apparatus and thedriver may be different. Therefore, by adjusting the applied voltage ofthe first electrically-controlled element 210, the viewing angle controlrange may be optimized according to the configuration requirements ofdifferent vehicle models. In addition, as different drivers havedifferent heights, the angle of viewing the display apparatus 10 is alsodifferent. Therefore, the viewing angle control range may be optimizedfor drivers of different heights by adjusting the applied voltage of thesecond electrically-controlled element 220. In other words, the methodof driving the display apparatus 10 may further includes tuning theapplied voltage (i.e., the third voltage) of the secondelectrically-controlled element 220 when the display apparatus 10 isoperated in the narrow viewing angle mode.

For example, referring to FIG. 1 and FIG. 7A to FIG. 7C, wherein FIG. 7Ato FIG. 7C are respectively transmittance distribution diagrams of thedisplay apparatus 10 when the second electrically-controlled element 220is applied with voltages of 3.1 V, 3.5 V, and 3.9 V, and the firstelectrically-controlled element 210 is applied with a voltage of 1.6 V.According to the figures, it is known that when the applied voltage ofthe second electrically-controlled element 220 is 3.1 V, a non-viewingarea of the display apparatus 10 within the viewing angle of 50 degreesmay be deviated from the front viewing angle direction along thedirection Y, and may be moved toward the opposite direction of thedirection Y as the applied voltage is increased. When the appliedvoltage is 3.9 V, the non-viewing area of the display apparatus 10within the viewing angle of 50 degrees may be deviated from the frontviewing angle direction along the opposite direction of the direction Y.Namely, by adjusting the applied voltage of the secondelectrically-controlled element 220, the display apparatus 10 may alsohave a second viewing angle control direction parallel to the directionY.

Referring to FIG. 7D at the same time, a curve D1, a curve D2, and acurve D3 respectively show brightness-viewing angle distributions (i.e.,narrow viewing angle brightness distribution curves) of the displayapparatus 10 along the direction Y (or the second viewing angle controldirection) of FIG. 7A to FIG. 7C including a horizontal viewing angle of35 degrees when the second electrically-controlled element 220 isapplied with voltages of 3.1 V, 3.5 V, and 3.9 V. The viewing anglecorresponding to a valley of the narrow viewing angle brightnessdistribution curve may be moved along the direction Y as the appliedvoltage (i.e., the third voltage) of the second electrically-controlledelement 220 is increased.

Referring to FIG. 8A, for example, the backlight module 100 may includea light guide plate 110, a light source 120, a diffuser 130, a reflector140, a prism sheet 150, and two optical brightness enhancement films 161and 162. The light guide plate 110 has a light incident surface 110 is,and a bottom surface 110 bs and a light-emitting surface 110 esconnected to the light incident surface 110 is and opposite to eachother. The light source 120 is disposed at a side of the light incidentsurface 110 is of the light guide plate 110. The reflector 140 isdisposed on one side of the bottom surface 110 bs of the light guideplate 110. The diffuser 130, the prism sheet 150, and the two opticalbrightness enhancement films 161 and 162 are sequentially disposed onone side of the light-emitting surface 110 es of the light guide plate110, wherein the prism sheet 150 includes a substrate 151 and aplurality of prism structures 153, and these prism structures 153 aredisposed on a surface of the substrate 151 facing the light guide plate110. To be specific, the backlight module 100 of the embodiment may be alight-collecting-type backlight module, but the invention is not limitedthereto. In another embodiment, as shown in FIG. 8B, the backlightmodule 100A may also adopt a viewing angle control sheet 170 (forexample, 3M LCF) to replace the prism sheet 150 of FIG. 8A, wherein theviewing angle control sheet 170 is disposed on one side of the twooptical brightness enhancement films 161 and 162 away from the lightguide plate 110. In another embodiment, the backlight module may also bea backlight module commonly used in a vehicle-mounted display apparatusor a general display apparatus, which is not limited by the invention.

Other embodiments are provided below to describe the invention indetail, wherein the same reference numerals denote the same or likecomponents, and descriptions of the same technical contents are omitted.The aforementioned embodiments may be referred for descriptions of theomitted parts, and detailed descriptions thereof are not repeated in thefollowing embodiments.

FIG. 9 is a schematic cross-sectional view of a display apparatusaccording to the second embodiment of the invention. FIG. 10A is aschematic diagram illustrating the arrangement relationship between thealignment direction of the alignment layer, the axial directions of theabsorption axes of the polarizers, and the axial direction of the slowaxis of the half-wave plate of FIG. 9 . FIG. 10B is a schematic diagramillustrating another arrangement relationship between the alignmentdirection of the alignment layer, the axial directions of the absorptionaxes of the polarizers, and the axial direction of the slow axis of thehalf-wave plate of FIG. 9 . FIG. 11A and FIG. 11B are transmittancedistribution diagrams of the display apparatus of FIG. 9 respectivelyoperated in a wide viewing angle mode and a narrow viewing angle mode.

Referring to FIG. 9 and FIG. 10A, a difference between a displayapparatus 10A of the embodiment and the display apparatus 10 of FIG. 1is that the display apparatus 10A further includes a third polarizerPOL3, a first compensation film 271, and a second compensation film 272,wherein the third polarizer POL3 is disposed between the half-wave plate250 and the second electrically-controlled element 220, the firstcompensation film 271 is disposed between the third polarizer POL3 andthe second electrically-controlled element 220, and the secondcompensation film 272 is disposed between the secondelectrically-controlled element 220 and the display panel 300.

It should be noted that the included angle between the axial directionof a third absorption axis AX3 of the third polarizer POL3 and the thirdalignment direction AD3 of the third alignment layer AL3 is between −15degrees and 15 degrees or between 75 degrees and 105 degrees. In theembodiment, the third absorption axis AX3 is, for example, parallel tothe third alignment direction AD3. In another embodiment, as shown inFIG. 10B, an included angle β′ between a third absorption axis AX3′ andthe third alignment direction AD3 may also be 90 degrees. Since therelative arrangement relationship between the first alignment direction,the second alignment direction, the third alignment direction AD3, thefourth alignment direction AD4, the axial direction of the firstabsorption axis, the axial direction of the second absorption axis AX2and the axial direction of the slow axis SX of the half-wave plate 250of the present embodiment is similar to that of the display apparatus 10of FIG. 1 , detailed description thereof may be deduced by referring torelated paragraphs of the aforementioned embodiments, which will not berepeated.

Moreover, the first compensation film 271 and the second compensationfilm 272 are, for example, biaxial compensation films (B-plate) orC-plate compensation films, and the sum of out-of-plane phaseretardation amounts (Rth) of the first compensation film 271 and thesecond compensation film 272 is between 200 nm and 1000 nm. For example,in the embodiment, the first compensation film 271 and the secondcompensation film 272 are, for example, biaxial compensation films, andthe sum of the out-of-plane phase retardation amounts is, for example,290 nm.

Referring to FIG. 11A and FIG. 11B at the same time, it is particularlynoted that, in the display apparatus 10A of the embodiment, theanti-peep performance of the display apparatus 10A in the first viewingangle control direction may be improved by setting the third polarizerPOL3, and the arrangement of the first compensation film 271 and thesecond compensation film 272 may expand the anti-peep range of thedisplay apparatus 10A.

FIG. 12 is a schematic cross-sectional view of a display apparatusaccording to the third embodiment of the invention. FIG. 13 is aschematic diagram illustrating the arrangement relationship between thealignment direction of the alignment layer, the axial directions of theabsorption axes of the polarizers, and the axial direction of the slowaxis of the half-wave plate of FIG. 12 . FIG. 14A and FIG. 14B aretransmittance distribution diagrams of the display apparatus of FIG. 12respectively operated in different display modes. FIG. 15 is aluminance-viewing angle curve diagram of the display apparatus of FIG.12 and the display apparatus of FIG. 1 operated in a narrow viewingangle mode.

Referring to FIG. 12 and FIG. 13 , the difference between a displayapparatus 10B of the embodiment and the display apparatus 10 of FIG. 1is that the display apparatus 10B further includes a third polarizerPOL3-A disposed between the half-wave plate 250 and the secondelectrically-controlled element 220, and the phase retardation amount ofthe second liquid-crystal layer LCL2 of the secondelectrically-controlled element 220 is smaller. It should be noted thatin the embodiment, an included angle β″ between the axial direction of athird absorption axis AX3″ of the third polarizer POL3-A and the thirdalignment direction AD3 is 10 degrees. Since the configuration of thethird alignment direction AD3 of the embodiment is the same as that ofthe third alignment direction AD3 of the third alignment layer AL3 ofthe embodiment of FIG. 1 , the included angle between the thirdabsorption axis AX3″ and the direction X of the embodiment is 95degrees. Moreover, different from the half-wave plate 250 of FIG. 1 , anincluded angle θ″ between a slow axis SX″ of the half-wave plate 250Aand the direction X of the present embodiment is 70 degrees.

Referring to FIG. 14A and FIG. 14B, since the third absorption axis AX3″of the third polarizer POL3-A of the embodiment is neither parallel norperpendicular to the third alignment direction AD3 of the thirdalignment layer AL3, when the display apparatus 10B is operated in thenarrow viewing angle mode, the non-viewing area thereof is shiftedrelative to the non-viewing area of the display apparatus of each of theaforementioned embodiments. For example, when the display apparatus 10of FIG. 1 is operated in the narrow viewing angle mode, the narrowviewing angle brightness distribution curve C2 along the direction X andincluding the front viewing angle (as shown in FIG. 15 ) shows that thedisplay apparatus 10 still has a relatively high brightness in a viewingangle range of 55 degrees to 60 degrees, and the emitted light of theviewing angle range may have adverse effects in special usagesituations. Therefore, in the present embodiment, when the displayapparatus 10B is operated in the narrow viewing angle mode, thenon-viewing area may be shifted (for example, shifted toward a largeviewing angle) through the above configuration of the third polarizerPOL3-A, so that the light output of the display apparatus 10B in theviewing angle range of 55 degrees to 60 degrees is suppressed (as shownby a curve C6 in FIG. 15 ), so as to meet different usage requirements.

Moreover, in the embodiment, by adjusting the phase retardation amountof the second liquid-crystal layer LCL2, the viewing angle range of thenon-viewing area of the display apparatus 10B may also be adjusted. Forexample, the range of the non-viewing area of the display apparatus 10Bis increased as the phase retardation amount of the secondliquid-crystal layer LCL2 is decreased.

Based on the above, in the display apparatus of an embodiment of theinvention, the electrically-controlled first liquid-crystal layer andsecond liquid-crystal layer are provided between the backlight moduleand the display panel. The included angle between the alignmentdirection on one side of the first liquid-crystal layer and thealignment direction on the other side thereof is between 75 degrees and105 degrees, and the included angle between the alignment direction onone side of the second liquid-crystal layer and the alignment directionon the other side thereof is between 165 degrees and 195 degrees,wherein the included angle between the alignment direction of the firstliquid-crystal layer close to the second liquid-crystal layer and thealignment direction of the second liquid-crystal layer close to thefirst liquid-crystal layer is between 30 degrees and 60 degrees, orbetween 120 degrees and 150 degrees, and two opposite sides of the firstliquid-crystal layer are provided with two polarizers with absorptionaxes perpendicular to each other. Through the above configuration, theviewing angle range of the display apparatus in at least one directionmay be electrically-controlled and switched to meet different usagesituations.

The foregoing description of the preferred embodiments of the inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform or to exemplary embodiments disclosed. Accordingly, the foregoingdescription should be regarded as illustrative rather than restrictive.Obviously, many modifications and variations will be apparent topractitioners skilled in this art. The embodiments are chosen anddescribed in order to best explain the principles of the invention andits best mode practical application, thereby to enable persons skilledin the art to understand the invention for various embodiments and withvarious modifications as are suited to the particular use orimplementation contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto and their equivalentsin which all terms are meant in their broadest reasonable sense unlessotherwise indicated. Therefore, the term “the invention”, “the presentinvention” or the like does not necessarily limit the claim scope to aspecific embodiment, and the reference to particularly preferredexemplary embodiments of the invention does not imply a limitation onthe invention, and no such limitation is to be inferred. The inventionis limited only by the spirit and scope of the appended claims.Moreover, these claims may refer to use “first”, “second”, etc.following with noun or element. Such terms should be understood as anomenclature and should not be construed as giving the limitation on thenumber of the elements modified by such nomenclature unless specificnumber has been given. The abstract of the disclosure is provided tocomply with the rules requiring an abstract, which will allow a searcherto quickly ascertain the subject matter of the technical disclosure ofany patent issued from this disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Any advantages and benefits described may notapply to all embodiments of the invention. It should be appreciated thatvariations may be made in the embodiments described by persons skilledin the art without departing from the scope of the present invention asdefined by the following claims. Moreover, no element and component inthe present disclosure is intended to be dedicated to the publicregardless of whether the element or component is explicitly recited inthe following claims.

What is claimed is:
 1. A display apparatus, comprising: a backlightmodule; a first electrically-controlled element disposed on thebacklight module and comprising: a first liquid-crystal layer; and afirst alignment layer and a second alignment layer, wherein the firstliquid-crystal layer is sandwiched between the first alignment layer andthe second alignment layer, and an included angle between a firstalignment direction of the first alignment layer and a second alignmentdirection of the second alignment layer is between 75 degrees and 105degrees; a second electrically-controlled element disposed on the firstelectrically-controlled element and comprising: a second liquid-crystallayer; and a third alignment layer and a fourth alignment layer, whereinthe second liquid-crystal layer is sandwiched between the thirdalignment layer and the fourth alignment layer, and an included anglebetween a third alignment direction of the third alignment layer and afourth alignment direction of the fourth alignment layer is between 165degrees and 195 degrees, wherein an included angle between the secondalignment direction and the third alignment direction is between 30degrees and 60 degrees, or between 120 degrees and 150 degrees; a firstpolarizer disposed between the backlight module and the firstelectrically-controlled element and having a first absorption axisparallel or perpendicular to the first alignment direction; a secondpolarizer disposed between the first electrically-controlled element andthe second electrically-controlled element and having a secondabsorption axis, wherein an axial direction of the second absorptionaxis is perpendicular to an axial direction of the first absorptionaxis; a half-wave plate disposed between the second polarizer and thesecond electrically-controlled element; and a display panel disposed onthe second electrically-controlled element.
 2. The display apparatus asclaimed in claim 1, wherein an axial direction of a slow axis of thehalf-wave plate is located between the axial direction of the secondabsorption axis of the second polarizer and the third alignmentdirection.
 3. The display apparatus as claimed in claim 1, wherein anincluded angle between the third alignment direction and a first viewingangle control direction of the display apparatus is 85 degrees.
 4. Thedisplay apparatus as claimed in claim 1, wherein an included anglebetween the first alignment direction or the second alignment directionand a first viewing angle control direction of the display apparatus is45 degrees.
 5. The display apparatus as claimed in claim 1, wherein thefirst absorption axis is parallel to the first alignment direction, andthe second absorption axis is parallel to the second alignmentdirection.
 6. The display apparatus as claimed in claim 1, wherein anincluded angle between an axial direction of a slow axis of thehalf-wave plate and a first viewing angle control direction of thedisplay apparatus is between 50 degrees and 80 degrees or between 140degrees and 170 degrees.
 7. The display apparatus as claimed in claim 1,further comprising: a third polarizer disposed between the half-waveplate and the second electrically-controlled element, wherein anincluded angle between an axial direction of a third absorption axis ofthe third polarizer and the third alignment direction is between −15degrees and 15 degrees or between 75 degrees and 105 degrees.
 8. Thedisplay apparatus as claimed in claim 7, further comprising: a firstcompensation film disposed between the third polarizer and the secondelectrically-controlled element; and a second compensation film disposedbetween the second electrically-controlled element and the displaypanel, wherein a sum of out-of-plane phase retardation amounts of thefirst compensation film and the second compensation film is between 200nm and 1000 nm.
 9. The display apparatus as claimed in claim 8, whereinthe first compensation film and the second compensation film arerespectively a biaxial compensation film or a C-plate compensation film.10. The display apparatus as claimed in claim 7, wherein the thirdabsorption axis of the third polarizer is neither parallel norperpendicular to the third alignment direction of the third alignmentlayer.
 11. The display apparatus as claimed in claim 1, wherein when thedisplay apparatus is operated in a wide viewing angle mode, a firstvoltage is provided to the first electrically-controlled element and thesecond electrically-controlled element, and when the display apparatusis operated in a narrow viewing angle mode, a second voltage is providedto the first electrically-controlled element and a third voltage isprovided to the second electrically-controlled element, the firstvoltage is smaller than the second voltage, and the first voltage issmaller than the third voltage.
 12. The display apparatus as claimed inclaim 1, wherein when the display apparatus is operated in a narrowviewing angle mode, a second voltage is provided to the firstelectrically-controlled element, the display apparatus has a narrowviewing angle brightness distribution curve, and a viewing anglecorresponding to a peak of the narrow viewing angle brightnessdistribution curve is moved along a first viewing angle controldirection of the display apparatus with a variation of the secondvoltage.
 13. The display apparatus as claimed in claim 1, wherein whenthe display apparatus is operated in a narrow viewing angle mode, athird voltage is provided to the second electrically-controlled element,the display apparatus has a narrow viewing angle brightness distributioncurve, and a viewing angle corresponding to a valley of the narrowviewing angle brightness distribution curve is moved along a secondviewing angle control direction of the display apparatus with avariation of the third voltage.
 14. A method of driving a displayapparatus, comprising: providing the display apparatus, wherein thedisplay apparatus comprises: a backlight module; a firstelectrically-controlled element disposed on the backlight module andcomprising: a first liquid-crystal layer; and a first alignment layerand a second alignment layer, wherein the first liquid-crystal layer issandwiched between the first alignment layer and the second alignmentlayer, and an included angle between a first alignment direction of thefirst alignment layer and a second alignment direction of the secondalignment layer is between 75 degrees and 105 degrees; a secondelectrically-controlled element disposed on the firstelectrically-controlled element and comprising: a second liquid-crystallayer; and a third alignment layer and a fourth alignment layer, whereinthe second liquid-crystal layer is sandwiched between the thirdalignment layer and the fourth alignment layer, and an included anglebetween a third alignment direction of the third alignment layer and afourth alignment direction of the fourth alignment layer is between 165degrees and 195 degrees, wherein an included angle between the secondalignment direction and the third alignment direction is between 30degrees and 60 degrees, or between 120 degrees and 150 degrees; a firstpolarizer disposed between the backlight module and the firstelectrically-controlled element and having a first absorption axisparallel or perpendicular to the first alignment direction; a secondpolarizer disposed between the first electrically-controlled element andthe second electrically-controlled element and having a secondabsorption axis, wherein an axial direction of the second absorptionaxis is perpendicular to an axial direction of the first absorptionaxis; a half-wave plate disposed between the second polarizer and thesecond electrically-controlled element; and a display panel disposed onthe second electrically-controlled element; providing a first voltage tothe first electrically-controlled element and the secondelectrically-controlled element to operate the display apparatus in awide viewing angle mode; and providing a second voltage and a thirdvoltage to the first electrically-controlled element and the secondelectrically-controlled element, respectively, to operate the displayapparatus in a narrow viewing angle mode, wherein the first voltage issmaller than the second voltage, and the first voltage is smaller thanthe third voltage.
 15. The method of driving the display apparatus asclaimed in claim 14, further comprising: tuning the second voltageprovided to the first electrically-controlled element when the displayapparatus is operated in the narrow viewing angle mode and has a narrowviewing angle brightness distribution curve, wherein a viewing anglecorresponding to a peak of the narrow viewing angle brightnessdistribution curve is moved along a first viewing angle controldirection of the display apparatus with a variation of the secondvoltage.
 16. The method of driving the display apparatus as claimed inclaim 14, further comprising: tuning the third voltage provided to thesecond electrically-controlled element when the display apparatus isoperated in the narrow viewing angle mode and has a narrow viewing anglebrightness distribution curve, wherein a viewing angle corresponding toa valley of the narrow viewing angle brightness distribution curve ismoved along a second viewing angle control direction of the displayapparatus with a variation of the third voltage.